Electric circuit interrupter



Oct. 28, 1947.

J, w. sJEAMAN ELECTRIC CIRCUIT INTERRUPTER Filed I larch 24, 1944 .7. 7////,///// f/////7///////. m l l I I J i Inventor: Joseph W. Seaman,

- His Attorney.

Patented Oct. 28, 1947 automa cmcm mrnaavr'rsa Joseph W. Seaman, Kennett Square, Pa., assignor to General Electric Company, a corporation of f New `York Application Mms zi, 1944, serial No. 521,913 '1 claim. (ci. zoo- 144) My inven'tion relates to electric circuit interrupters, and more .particularly to air circuit interrupteis of the type wherein the arc is to be interrupted within connning or partially confining means, such as an arc chute.

Herctofore electric circuit interrupters of the above mentioned type have comprised -a plurality of relatively movable contacts arranged adjacent to an arc chute with means such as magnetic blowout coils, air Jets or the like, for forcing the arc into the arc chute where it can be interrupted. In some of these prior art constructions where the arc is drawn' outside of the arc chute and `means are provided to force it into the arc chute,

a current level is sometimes reached with the arc core havingsuch a large diameter that the magnetic blowout means, for example, cannot force the arc into the part of the chute where the interruption takes place with the resultthat failure occurs; Y

It is an object of my invention to provide an improved electric circuit breaker in which it is impossible to have a failure to interrupt the circuit due to `failure to move the arc into the interrupting part'of the arc extinguishing structure.

It is another object of my invention to provide a new andimproved electric circuit interrupter in which the arc is drawn in the part of the arc extinguishing structure where interruption ilnally occurs.

.I t is another obiect of my invention to provide an electric circuit interrupter including aplurality of parallel arranged contacts separable within narrow slots of an insulating, arc extinguishing structure.`

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularityin the claims annexed to and forming a part of this specification.

For a" better understanding of my invention reference-may be had to the accompanying drawing in which Fig. l is afront view, partly in section, of an electric circuit breaker embodying my invention: Fig. 2 is an exploded view in perspective of the arc extinguishing structure for one pole of the electric circuit interrupter, shown in Fig. 1: Fig. 3 is an enlarged sectional view taken on line 3-3 of Fig. `-1, and Fig. 4' is a sectional view taken on line 4--4 of Fig. 3.

It has been discovered that an arc can very eil'ectively bo interrupted when coniined within a narrow slot contained in an insulating arc extinguishing structure. If the contacts of an electric circuit interrupter were separated so as yto draw the arc directly within such a narrow slot the interruption could take place there and no means would be required as in prior art devices to force the arc to the point in the arc extinguishing structure where interruption can take place, the arc being drawn at a diiierent point. Due to the high currents which must be carried by the contacts of electric circuit interrupters, the contact area from the standpoint of successfully withstanding the burning action of the arc, must be quite large so that such contacts would be too large to operate within the narrow slots which I have discovered are particularly well adapted to effectively interrupt an. arc drawn within such slots. My invention is concerned with an ar- ,rangement in which one or more relatively narrow contacts connected in multiple are provided so that each contact can move within the narrow slot most effective for arc interruption, and the number of such multiple arranged contacts being dependent upon the magnitude of the currentto be carried and interrupted.

Referring now to the drawing, I have illustrated an electric circuit interrupter generally indicated at lll, which might be a single-pole or multiple-pole circuit interrupter. In Fig. 1 a three-pole circuit interrupter is indicated 'comprising an insulating casing Il with three upper terminals i2, and three lower terminals I3 mounted on the casing. Although each pole of the circuit interrupter i0 may include one. two, or more contacts in multiple, I have specifically illustrated an arrangement in which two contacts are provided in multiple. These contacts are not visiblevin Fig. 1 but the supporting rods I4 for the movable contacts are clearly visible in Fig. 1 as well as in Figs. 3 and 4. With the slots of the of the circuit breaker disclosed in Fig. 1 are not my invention but are disclosed and claimed in the copending application of John A. Favre, Serial ;No. 555,630, filed September 25, 1944, and assigned to the same assignee as the present application.

Mounted in the upper part of casing Ii of circuit interrupter Ill are a plurality of arc extinguishing structures or arc chutes Il, one for each ci contacts and means must be provided to immepole of the `circuit interrupter. Each of these arc diately transfer this arc to all of the multiple conchutes, best shown in Figs. 2, 3, and 4, preferably tacts arranged in parallel since the ability for comprises, a structure which may be removed as one slot to interrupt current is limited. To this a unit if desired. Furthermore, these arc chutes g end I provide the wall or barrier I8 between the are formed of an insulating material and preferslots I8 with a plurality oi openings 82 to pro.. ably a bonded asbestos compound which might vide uniform distribution o! the gases and concomprise a phosphoric asbestos compound which sequently to produce parallel arcs, one in each could be molded to the desired shape. The arc slot with the current shared substantially equally chute might also be made from asbestos board i between the arcs in the respective slots. Almachined to the proper shape. Each arc chute or though the openings 82 have been indicated as arc extinguishing structure comprises a'pair of circular openings, it should be understood that outer walls I6 and I1 which are adapted to be this is not essential and any other means for obarranged in spaced parallel relationship. The arc taining distribution of the arc gases between the extinguishing structure is divided into a pluslots I8 such as irregular shaped openings can oi rality of narrow slots such as I8, by one or more course be used.

insulating barriers I8. Since only two multiple The arc chute was designed by varying the size contacts for each pole are illustrated, only a thereof, the slot spacing and the arrangement of single insulating barrier I8 is required. Each the holes 82 for optimum current interruption. of the members IB and I1 is provided with an 20 The greater the current tobe carried by each conextension at one edge thereof which cooptact in each slot, the wider the slot and the larger crates with an extension 2| of insulating barrier the openings between slots, I have found g, slot or wall IS to determine the spacing between the with of less than onehalf inch to be very desirmembers I6, I1 and I9. 'I'he edge of barrier I8 able. An arc chute having a 1'. inch slot width opposite the edge upon which extension 2I is g5 with the openings 82 being inch in diameter mounted is adapted to iit within a slot formed by spaced on 1/2 inch centers with alternate rows of cutaway portions of members I6 and I1. 'I'he are holes lling the intervening space appeared to chute is held together as a unitary structure by yield the best results. any suitable means, which is indicated in the In order to c'ool the arc gases a suitable muiiier drawingasby pins 22,one of which passes through so may be provided at the upper end of each are the extensions 20 and 2| and the other ci which chute. Such a muiiler may comprise a series of passes through openings 23, 2l and 25 in mem- U-shaped members arranged with the alternate bers IS, I1 and I9, respectively. U-shaped members inverted. This can be ac- Supported from the back wall of casing II in complished by supporting as by molding into such a manner as to extend within the slots I8 85 member I6, for example, a plurality of inverted of the arc chute .I5 are stationary contacts 26 U-shaped members 88 of a length dependent (Figs. 3 and 4) which are connected in parallel upon the spacing between members I6 and I1. or multiple by ilexible copper conductors 2l Similarly supported from the member I1, on the suitably connected to terminal I2. In order to other hand, are the upright U-shaped members prevent anymagnetic forces produced by virtue 34', Preferably these U-shaped members nest toof the current flowing through flexible conducgether so that the adjacent ends of two inverted tors 2l from terminal I2 to the bottom of sta- U-shaped members Il extend within one of the tionary contacts 26 from causing the arc to move U-shaped members 8| and vice versa. In this downwardly on contacts 2i rather than upmanner a discontinuous sinusoidal metallic coolwardly, a magnetic shield 28 is provided which 45 ing member is provided against which the hot may comprise copper plated steel, or the like. gases impinge. This muiiler construction forms This magnetic shield is mounted between iiexible no part of my invention but is disclosed and conductors 21 and contacts 26. A rivet 29 holds claimed in the copending application tiled conthe shield 28 and exible conductors 21 and the currently herewith of Charles H. Titus, Serial terminals I2 in proper alinement as a unitary as- 80 No. 527,912, assigned to the same assignee as the sembly. This arrangement of the stationary conpresent application, now Patent No. 2,408,352, lstacts is not my invention but is disclosed in the sued September 24, 1946. above-mentioned Favre application. In view of the detailed description given above Cooperating movable contacts 88 are adapted the operation of the circuit interrupter of my to be supported on movable conducting supportsa invention will be obvious to those skilled in the ing rods I 4 so as to move within Vthe narrow slots art. Upon separation of the contacts 28 and 88 I8 of the arc chutes I 5.- These rods are elecwithin slots I8 (two parallel sets of contacts and trically and mechanically interconnected as inditwo slots being shown, although three or more cated at 8l in Fig. 4. The movable contacts SII might be utilized), an arc is drawn between one are arranged so that the entire motion thereof is a0 set of contacts 28 and 88 within the associated within narrow slots I8 so that the arc is always slot I8. The arc gases formed are equalized imdrawn at the place where it is to be interrupted p mediateb, and distributed between the slots, and no means are required to force the arc into an thereby eqlllizln the temperature gradient bearc chute, -as ,ylasv .the case inprior art constnlcengm tween the slots and hence permitting parallelarcs tions. The open position of movable contacts u to be formed, one in each slot. Since the arc is is indicated by dotted lines in Fig. 3. The movdrawn in the portion of the arc extinguishing able contacts 38 are provided with a contact surstructure where interruption is to occur, failure face which is very narrow in the direction at right to interrupt by virtue oi failure to move the arc angles to the direction of contact motion as cominto the arc chute is impossible. The narrow pared to the dimension of the contact surface 7o slot geometry of the arc chute causes immein the other direction. diate interruption oi the arcs and the hot arc Upon separation of stationary contacts 28 and gases impinging against 'the members 33 and 8l movable contacts 30 an arc will be drawn. Due of the mumer are rapidly cooled before leaving to slight mechanical differences between the conthe arc chute. taets, this arc will usually be drawn at one set 7l While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. In an electric circuit interrupter comprising an arc extinguishing structure including a plurality of narrow slots displaced from each other by a wall `of insulating material, a plurality of pairs of electrically parallel relatively movable cooperating contacts so mounted as to be respectively separable in said slots for drawing an arc within at least one of said slots, and means including openings in said wall for lproviding communication between said slots to tend to produce a uniform distribution of gases between said slots as Well as to cause a plurality of parallel f arcs to occur,-one in each slot.

2. In an electric circuit interrupter comprising an arc extinguishing structure including an insulating member defining a plurality of narrow` slots with a wall of insulating material between said slots, a stationary Contact mounted in each slot, a plurality of cooperating movable contacts arranged one in each slot and movable therein so as to draw an arc in at least one of said slots upon separation of said stationary and movable contacts, said movable contacts being mechanically and electrically interconnected exteriorly of said arc chute, the number of said contacts and slots depending upon the current expected to be carried by said contacts, and a plurality of openings in said wall between said slots to tend to produce a uniform distribution of gases between said slots as well as to cause a plurality of parallel arcs to occur one in each slot.

3. An are extinguishing device'for a circuit interrupter comprising two spaced parallel-connected stationary contacts, two respectively cooperating spaced parallel-connected substantially simultaneously movable contacts, and insulating means forming two narrow slots having substantially the same width with an intervening wall of insulating material, said insulating means being adapted to be mounted on the circuit breaker with said contacts and the respectively associated cooperating movable contacts respectively positioned in said slots to strike an arc within at least one of said slots upon separation of the respectively cooperating contacts therein under predetermined current conditions in a circuit through the circuit breaker and to hold the extremities of said arc until extinction thereof.

4. An arc extinguishing device for a circuit interrupter havinga plurality of spaced parallelconnected stationary contacts and a plurality'of respectively cooperating spaced parallel-connected substantially simultaneously movable con- I tacts, insulating meansforming a plurality of narrow slots with an intervening perforated wall of insulating material between each of two adjacent slots, said insulating means being adapted nected stationary contacts, two respectively cooperating spaced parallel-connected substantially simultaneously movable contacts, and insulating means forming two narrow slots with an intervening wall of insulating material, said insulating means being adapted to be mounted on the circuit breaker with said contacts and the respectively associated cooperating movable contacts respectively positioned in` said slots and said intervening wall being perforated for permitting a uniform distribution of gases between the slots and for causing a plurality of parallel arcs to occur one in each slot. i

6. In an arc extinguishing device for a circuit interrupter having a plurality of spaced parallelconnected stationary contacts and a plurality of respectively cooperating spaced parallel-connected substantially simultaneously movable contacts, insulating means forming a plurality of narrow slots with an intervening wall of insulating material between each of two adjacent slots;

said insulating means being adapted to be mounted on the circuit breaker with one stationary contact and the respectively associated cooperating movable contact in each slot and said walls being provided with a plurality of openings for permitting a uniform distribution of gases between the slots and for causing a plurality of parallel arcs to occur one in each slot.

7. An arc extinguishing device for a circuit interrupter'having a plurality of spaced parallelconnected stationary contacts and a plurality of respectively cooperating spaced parallel-connected substantially simultaneously movable contacts, insulating means forming a plurality of narrow slots of substantially the same width with an intervening perforated wall of insulating material between each of two adjacent slots, said insulatingv means being adapted to be mounted on the circuit breaker with one stationary contactV and the respectively associated cooperating movable contact positioned in each slot to strike an arc within at least one of said slots upon separation of the respectively cooperating contacts therein under predetermined current conditions in a circuit through the circuit breaker and to hold the extremities of said arc until extinction thereof.

JOSEPH W. SEAMAN.

REFERENCES CITED The following references are of record in the nie of this patent:

UNITED STATES PATENTS Number Name Date 1,955,961 ,Jackson Apr. 24, 1934 2,032,149 Rawlins Feb. 25, 1936 2,039,080 Hutl'stutter Apr. 28, 1936 2,077,276 Slepian Apr. 13, 1937 2,088,489 Slepian July 27, 1937 2,109,216 Huifstutter Feb. 22, 1938 2,192,772 MacNeill Mar. 5, 1940 2,285,643 Beiersdorf et al. June 9, 1942 2,338,715 l Graves, Jr. Jan. 11, 1944 2,367,937 Gates Jan. 23, 1945 FOREIGN PATENTS Number Country Date 403,068 Germany Sept. 26, 1924 

